Rheostat



(No Model.)

A. C. CAREY.

Patented May 14, 1895.

UNITED STATES PATENT OFFICE.

AUGUSTUS U. CAREY, OF LAKE PLEASANT, MASSACHUSETTS.

RH EO STAT.

SPECIFICATION fOImIlg part Of Letters Patent N0. 539,216, dated May 14,1895.

Application filed February 26, 1895. Serial No. 539,779- (No model.)

To all whom it may concern.:

Be it known that I, AUGUSTUS C. CAREY, a citizen of the United States,residing at Lake Pleasant, in the county of Franklin and State ofMassachusetts, have invented a certain new and useful Improvement inRheostats, of which the following is a full, clear, and exactdescription.

This invention relates more especially to the construction of thewire-holding spool, and the laying on of the wire and insulating andprotecting it. The spool has a body of metal and an insulatingr barreland heads of mica, or other refractory and insulating material, and thewire is wound thereon in layers, which layers and the various turns ofwire thereof areinsulated from each other. The invention comprises thesemain and other minor features of construction, as hereinafter describedand claimed.

In the accompanying drawings, illustrating this invention, in theseveral gures of which like parts are similarly designated, Figure l isa side elevation; Fig. 2,v a vertical section. Fig. 5 is a diagramillustrating the Winding of the spool. Fig. iis a cross-section on line4t A, Fig. l, showing the under side of the top head of the rheostat.Fig. 5 is a cross-section on line 5 5, Fig. l, showing the upper side ofthe lower head; and Fig. 6 is a cross-section on line 6 6, Fig. l.

The lower head ais made with a hub or boss a', the interior of which ismade tapering so as to be frictionally fitted to an electrolier or otherfixture without the necessity of turning the rheostat, thus avoiding thedanger of twisting the conductors. A set screw a2 may be used to fix therheostat in position. A central tube o is secured in the boss a by a setscrew b. The top head c is made with aboss c', which is fitted to thetube b, as by a setscrew c2. The tube b extends beyond the boss csufficiently far to admit of the lamp or other object being securelyfitted thereto in any suitable manner.

d is the return or leading-out conductor. The leading-in conductor e, eis divided so as to include the rheostat, the part c extending from thedistributing plant to the rheostat and the part e extending from therheostat to the lamp or other obil ect to be supplied.

These conductors are arranged within the tube h.

The adjacent faces of the heads a and c are supplied with one or morelayers (dat rings) of mica, f, g, or other appropriate refractory andinsulating material, which may be riveted or otherwise secured thereto.

The head a has secured to its mica lining the contact spring h, which Iprefer to provide with a roller contact h', and this spring is connectedby wire h2 with the leading-in Wire c, said wire h2 extending through ahole b2 into the tube b. The head c is provided with a contact plate iapplied to the mica lining, and having its ends t" turned down to formstops. This contact plate is connected by wire 2 passed through a slotb3 in the tube b, with the leading-out section e of the dividedleadingin wire e, e'.

The spool containing the rheostat or resistance wire is composed of ametallic barrel 7c and heads 7c', k2, arranged to be revolved about thetube l), a knob or handle l being applied to the head 7c for thispurpose. The spool may be supported so as to be thus freely revolved,upon a coiled spring m, interposed between it and the lower head aandencircling the tube b.

The barrel of the spool is provided with a tube or jacket a, of mica orother refractory and insulating material, and the adjacent faces of themetallic heads, 7c', le?, are provided with a series, three, more orless, of mica rings o, which may be secured to such heads in anysuitable manner. I prefer to use a series of three rings and securelyrivet the spool next adjacent to the metallic heads to such heads,leaving the internal ring free. A series of contact pieces p, p,p2,p3,more or less, are secured to an intermediate one of the mica rings o inany suitable manner, and a contact piece q is secured similarly to themica rings of the upper head of the spool, and the contact pieces p3 andq are connected by a connecting strip or Enger rr, which is secured toeach and extends thence above the spool and into wiping contact with thecontact platee' of the upper head of the rheostat, the projections t',t', of such contact plate fr' forming stops to limit the movement of thespool by arresting the movement of the finger.

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The spool is wound with wire, s, in insulated layers, and I prefer towind the spool in the following manner, referring more especially now todiagram Fig. 3: I prefer to use silkcovered German silver wire, and thenaked portion thereof is first `secured to the contact piece p, and isythen wound about the spool from one end to the other and coated with acoating of liquid cementitious matter of 're= fractory and insulatingnature, s. I have found an efficient mixture for this purpose to consistof water-glass and. finely powdered chalk of proper consistence tospread easily. This cementis thoroughly applied tothe layer of wire soas to cover it externally and to enter in between its turns; and afterso coating the layer, the winding is continued to the starting point,and another layer of cement applied, and then another layer of wire andanother layer of cement, and finally, thefourth layer of wire and fourth`layerof cement yandk the wire is then stripped'of its silk covering fora short distance and the ynaked port-ion wound once or more Varound thecontact p", the-naked wire having been passed to the'far side of saidcontact to begin the winding, and

then a second winding of four layers of wire with interposed cement `isplaced Iupon the spool and the silk covering again stripped from thewire andthcwire woundabo'ut contact p2, and another turn of vfourlayers'of Wirev applied to the spool alternating with l'ayers of cement,and theendof the wire is then finally stripped and wound around vthecontact p3 in such manner as to be in intimate union with the nger'orstript". 1 Care should be taken that the cement be thoroughly-dried,otherwise there is danger of short circuitin'g.

In Fig. 2, for clearness in thedrawingsfl have shown three layersofwire, but it is to be understood that ea'chvof these layers repre'-sents in point of fact four turns of th'ewire, asjust described,and thesaineis true of Fig. 6.

The operation is obvious, but it, may `be stated that if kthe contactroller'hbe lbrought into contact with the contact p, the current willpass through the four layers of wire first wound on to the'spool and gothence to contact p', and then through-the ksecond four layers of wireto contact p2, and then through the final four layers of wirelto contactp3, and thence through the strip or iingerr to con-tact plate t', and soon to the lamp, thus putting in the full measure of resistance. l Anyless measure of resistance may be included in the circuit by vmovin-gthe spool so as to place one or the other of contacts p' or p2, inengagement with the contact roller h. If tlie contact piece p3 be placedin engagement with the contact Iroller h,f'obvi'ously the 'current goesdirectly therefrom through the linger fr to the lamp; and so, also,obviously,if the spool be turned so as to move-its contactpiece p beyondthe contact roller h', (tothe right, Fig. 3,) then 'the current isV shutout from the lamp or other object altogether. Thus the rheostat may beused not only for purposes of resistance, but also to turny on and edthe current fromtheobject to be supplied.

An outer casing t may be applied between the heads a and c, and saidcasing may be provided with openings t', t', for purposes ofventilation. Y

l. In a rheostat having heads or ends, a central tube upon which theyare mounted and through which the main conductors pass, refractory andinsulating linings for the adjacent Vfaces of said heads, contactdevices ap' plied to such linings and connected with the leading-inconductor, and a rotary spool provided with a series of layers of wireinsulated from one anothe'randfrom'the s'pooland pro* vided withcontacts-for inclusionin the main circuit, substantially as4 and for thepurpose described.

2. In a rheostat having heads or ends, a central'ftub'eupon which theyare mounted and through which the main conductors pass, refractory andinsulating linings for the adjacent faces of said heads, contact devicesapplied tosuch linings andconnected with the leading-in conductor, and arotary spool arrangeduponsuch tube'between the heads and havinga jacketyof refractory and insulating material, aseries lof layers of wireinsulated from one another,and contactsfor including such layers of'wire'lin Ithe mai-n circuit, substantially as described.

3. In a rheostat having r heads or ends7 a central tube upon which theyaremounted and through which the main conductorspass, refractory andinsulating linings for 'the adjacent faces of said heads, contactdevices applied to 'such linings and'connectedwith the leading-tinconductoigand a rotary spool hav- 4ing a'barre'l vand heads lof metaljacketed with a refractory 'and insulating material, such as Y mica, iaseries of layers of wire wound about such yjacketed spool and Ainsulatedfrom one f another', and aseries of independent contacts for including'any number of such layers of wire inthe main circuit, substantially'asdescribed.

` 4. In a rheostat having heads or ends, a

y-central 'tube upon whichtheyare 'mounted and through which the lnainconductors pass, refractory andinsulating linings for the adjacentfa'cesof said heads, contact devices applied to such linings andconnected withthe leading-in conductor, anda rotary spool having an vinner jacket ofrefractory and insulating material, a series of layers of wire arrangedupon such jacketed spool andinsulated from one another andrneans to cutinto and out of the main circuit any number of such layers of wire,substantially as described.

In testimony whereof I have hereunto set rny h'and vthis 23d'day ofFebruary, A. D. 1895.

AUGUSTUS C. CAREY.

' Witnesses:

HATTIE E. HAsKINs WALTER S. ROBINSON.

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